Bochy said Thursday that Zito was slated for possible relief duty that night, but downplayed the development by indicating that other starters -- whom he wouldn't name -- also would be "live" in the bullpen.

Zito is 4-8 with a 5.09 ERA in 21 starts this season, including 0-7, 9.97 in nine road assignments. The Giants are 2-8 in the last 10 games started by Zito, who's 0-5 with a 6.66 ERA in that span. He has one victory in his last 17 outings.

If Zito doesn't start, right-hander Guillermo Moscoso is a leading candidate to replace him. Moscoso relieved Zito in Tuesday's series opener against the Phillies and allowed two runs in 2 2/3 innings.

Chris Haft is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.